It is apparent that responses to environmental challenges (including brain damage) are a function of the interaction of many complex factors. Young and old organisms respond to malnutrition differently and the sensitivity to such challenges is a function of these of the subject. We will investigate the effects of differential maintenance conditions on behavior changes associated with septal lesions. We will investigate the interactions between malnutrition (including protein and vitamins) and septal lesions in young and old animals and how the effects of malnutrition are influenced by differential and non-nutritive maintenance conditions. We will continue to compare the effects of specific brain damage, septal lesions, which results in loss of behavioral plasticity with loss in flexibility induced by malnutrition or aging. Such a comparison may allow us to better understand the unique and common characteristics of different forms of physiological insult in determining behavior. While extrapolation of animal data to the human condition is always difficult, the utility of animal models is readily apparent. It is our belief that this series of experiments will contribute to a more quantitative as well as qualitative understanding of variables critical in determining relative resiliency of an organism to environmental challenges. BIBLIOGRAPHIC REFERENCES: Burright, R.G., Donovick, P.J., & Zuromski, E.S. Septal lesions and experiential influences on saline and saccharin preference-aversion functions. Physiology and Behavior, 1974, 12, 951-959; Donovick, P.J. A metachromatic stain for neural tissue. Stain Technology, 1974, 49, 49-51.